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FMEA Ratings

Comprehensive Failure Mode and Effects Analysis rating system for effective risk assessment

Access interactive tables for Severity (S), Occurrence (O), Detection (D), and Action Priority ratings based on AIAG & VDA FMEA Handbook standards.

Severity (S) Rating

Severity is a rating corresponding to the seriousness of the effect of a potential failure mode. It evaluates the impact of a failure on the customer, manufacturing process, or end product. The rating ranges from 1 (no effect) to 10 (hazardous without warning), considering impacts to your plant operations, shipping facilities, and end users. This assessment helps identify critical failure modes that require immediate attention and preventive measures.

SEffectImpact to Your PlantImpact to Ship-to Plant (when known)Impact to End User (when known)
10HighFailure may result in health and/or safety risk for the manufacturing or assembly workerFailure may result in health and/or safety risk for the manufacturing or assembly workerAffects safe operation of the vehicle and/or other vehicles, the health of driver or passenger(s) or road users or pedestrians
9HighFailure may result in in-plant regulatory noncomplianceFailure may result in in-plant regulatory noncomplianceNoncompliance with regulations
8Moderately high100% of production run affected may have to be scrappedLine shutdown greater than full production shift; stop shipment possible, field repair or replacement required (Assembly to End User) other than for regulatory noncompliance.Loss of primary vehicle function necessary for normal driving during expected service life
7Moderately highProduct may have to be sorted and a portion (less than 100%) scrapped; deviation from primary process, decreased line speed or added manpowerLine shutdown from 1 hour up to full production shift; stop shipment possible, field repair or replacement required (Assembly to End User) other than for regulatory noncomplianceDegradation of primary vehicle function necessary for normal driving during expected service life
6Moderately low100% of production run may have to be reworked off lineLine shutdown up to one hourLoss of secondary vehicle function
5Moderately lowA portion of the production run may have to be reworked off line and acceptedLess than 100% of product affected; strong possibility for additional defective product; sort required; no line shutdownDegradation of secondary vehicle function
4Low100% of production run may have to be reworked in station before it is processedDefective product triggers significant reaction plan; additional defective products not likely, sort not requiredVery objectionable appearance, sound, vibration, harshness, or haptics
3LowA portion of the production run may have to be reworked in station before it is processedDefective product triggers minor reaction plan; additional defective products not likely, sort not requiredModerately objectionable appearance, sound, vibration, harshness, or haptics
2LowSlight inconvenience to process, operation, or operatorDefective product triggers no reaction plan; additional defective products not likely, requires feedback to supplierSlightly objectionable appearance, sound, vibration, harshness, or haptics
1Very lowNo discernible effectNo discernible effect or no effectNo discernible effect
Source: AIAG & VDA FMEA Handbook

Frequently Asked Questions (FMEA Ratings & Rankings)

1. What are the standard FMEA Severity, Occurrence, and Detection (SOD) ratings?

FMEA ratings typically use a scale from 1 to 10 to evaluate risk. Severity measures the impact of a failure (1 = no effect, 10 = safety risk), Occurrence ranks the probability of the failure happening, and Detection assesses how likely the current controls will find the failure before it reaches the customer. Using a standardized FMEA severity table is crucial for consistent risk assessment across engineering teams.

2. How do I use the FMEA Severity Table 1-10 according to AIAG & VDA standards?

The latest AIAG & VDA FMEA Handbook provides updated criteria for the 1-10 scale. A rating of 9 or 10 always indicates a potential safety or regulatory non-compliance issue. In the new standards, the focus has shifted from just calculating a number to understanding the functional impact of each failure mode to ensure high-quality manufacturing and design.

3. What is the difference between RPN and Action Priority (AP) in FMEA?

While the Risk Priority Number (RPN) is calculated by multiplying Severity x Occurrence x Detection, the new Action Priority (AP) system uses a logic-based table to categorize risk as High, Medium, or Low. AP is now preferred over RPN because it prioritizes the combined impact of severity and occurrence, rather than just the final product of three numbers.

4. Where can I find a PFMEA and DFMEA Occurrence Table?

You can access comprehensive PFMEA (Process FMEA) and DFMEA (Design FMEA) occurrence tables on our site. These tables help you assign a ranking from 1 (nearly impossible occurrence) to 10 (persistent failure) based on historical data, preventive controls, and predicted failure rates during the design or production phase.

5. Why is a Detection ranking of 10 critical in a risk assessment?

In FMEA, a Detection ranking of 10 means there is absolutely no control in place to detect the failure mode, or the failure is undetectable. This is a high-risk scenario. Even if the occurrence is low, a high detection ranking often triggers an immediate need for improved inspection methods or automated sensors to protect the end-user.